Airbag control unit with part number 5WK42851

What does the airbag control unit 5WK42851 do?

The airbag control unit 5WK42851 is the hub of the SRS restraint system for Renault. It processes the readings from the crash sensors, determines within milliseconds in a crash which airbags and seatbelt pretensioners to trigger, and checks the entire system continuously. Faults appear via the airbag warning light.

This includes constant self-testing of wiring, sensors and output stages. The unit compares the results with stored specifications.

After a crash, the control unit saves crash data and then locks itself.

Why does the control unit 5WK42851 fail?

The most common cause is crash data saved after an accident, even when no airbag has deployed; an ordinary diagnostic tool cannot erase it. Other causes include aged electronic components, cold solder joints, moisture and corrosion on connectors, as well as voltage spikes, for example from a weak battery or a jump start.

Stored crash data is enough to cause a fault, even if the electronics have suffered no damage at all. The other causes stem from ageing, moisture or fluctuations in power, and they cannot be reliably told apart without a read-out.

How can you tell that the 5WK42851 is defective?

Typical signs are the airbag warning light in the instrument cluster, which lights up permanently or from time to time, and an error message in the instrument cluster. In addition, the diagnostic tool cannot establish a connection to the control unit and the fault memory cannot be cleared.

If the light is on, airbags and seatbelt pretensioners may not deploy in an emergency. For that reason, the warning deserves a prompt check.

Only the fault memory shows whether the control unit itself is affected. The warning light reports the finding, but does not name the cause.

Which vehicles is the 5WK42851 fitted in?

This list lets you check whether your car matches the part number. The airbag control unit 5WK42851 is fitted in these vehicles: Renault Espace III (1996-2002).

The overview lists these vehicles:

• Renault Espace III (1996-2002)

On the one hand, compare the part number on the label of the removed unit with this page; this only makes sure that you have the right unit in front of you. On the other hand, have the fault memory read out, because only this result shows whether the control unit is defective or whether a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 550346000, 6025308852F, 6025313596F, 6025371287.

How does the repair of the 5WK42851 work?

First have the fault memory read out and attach the log. Then disconnect the battery and only then remove the control unit. Afterwards create a repair order online and send in the unit well packed. Processing at Airbag24 usually takes 3–4 working days.

Airbag24 checks the unit on the test bench, repairs defective components, deletes stored crash data and carries out a function test. Your own unit is returned to you afterwards.

Our repairs come with 2 years' statutory liability for defects. The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.

How does the control unit 5WK42851 get to Airbag24?

The unit is sent in as a parcel; alternatively, UPS collects it for an extra charge. The return after repair is likewise made by UPS.

The printed repair order is enclosed with the parcel, and the unit must be packed shock-proof.